In the recent years where diversified kinds of electronic parts are fed in diversified modes and a larger number of electronic parts are mounted on each printed circuit board in the field of electronic parts mounting, it is often practiced to manufacture a printed circuit board with a parts mounting system which comprises a plurality of mounting units for electronic parts of plural kinds or a single kind.
Employed as a method to prepare operating instruction data for mounting units for electronic parts ("operating instruction data for the mounting units for the electronic parts" will hereinafter be referred to simply as mounting data) is a method for preparing mounting data by inputting such data as on location, dimension and the like of the electronic parts to a CAD system intended for designing a printed circuit board for mounting electronic parts, in an attempt to prepare mounting data efficiently and with higher precision.
In order to operate a plurality of mounting units for electronic parts ("the mounting units for electronic parts" will hereinafter be referred to simply as mounting units) with high efficiency by equalizing mounting time with each mounting unit as much as possible, however, it is necessary to employ a method for determining which parts are to be distributed to which mounting units.
Description will be made of a method for distributing electronic parts to the mounting units in a known electronic parts mounting system.
1. In mounting data for a single printed circuit board, an electronic part of a kind specified for a specific mounting unit ("the electronic part which is specified for a specific mounting unit" will hereinafter be referred to simply as a fixed part) is distributed to the specified mounting unit and such a distribution is repeated until no fixed part remains.
2. Then, a mounting time of each mounting unit to which the fixed parts have been distributed is calculated, and a mounting time for each remaining kind of electronic parts is calculated by multiplying a number of the parts by a mounting time for each single part.
3. Then, an electronic part which is calculated to have a the maximum mounting time is distributed to a mounting unit having the minimum mounting time, and such a distribution is repeated until no electronic part remains.
Thus, all the electronic parts are distributed to the mounting units such that each unit will have an equalized mounting time.
However, the foregoing known parts distributing method poses problems which are described below.
This method allows electronic parts of one kind to be distributed only to a single mounting unit. Therefore, when the kinds of electronic parts to be mounted on a single printed circuit board is in a small number and there are a large number of electronic parts of a same kind, it is hard to sufficiently equalize the mounting time of each mounting unit.